In a wireless communication system, base stations and mobile stations transmit signals in consideration of a channel coding scheme and a diversity gain in order to achieve reliable communication at a high speed.
Tarokh suggested space-time block coding for communication in a Rayleigh fading channel by means of multiple transmission antennas. Alamouti suggested a method capable of a diversity gain, with a system using two transmission antennas as a model.
Meanwhile, currently, an Orthogonal Frequency Division Multiple Access (OFDMA) scheme is being discussed as a wireless transmission scheme for the next-generation wireless mobile communication system.
According to the OFDMA scheme, a base station allocates a different number of subcarriers depending on data rates required by mobile stations, thereby efficiently distributing resources. In addition, the OFDMA scheme is suitable for a communication system using a large number of subcarriers, and can be efficiently used in a system having a wide area cell where a time delay spread is large.
However, since signals are mapped in units of symbols for each mobile station in a wireless communication system using the OFDMA scheme, it is impossible to obtain a diversity gain unless a channel coding is performed. Moreover, even though a channel coding is performed in the wireless communication system, only a small amount of diversity gain can be obtained. In order to maximize the diversity gain, it is necessary to use multiple antennas. However, when multiple antennas are used, there is a problem in that the configuration of a receiver is more complicated in order to remove interference between antennas.